"We're the smartest people, we're the most loyal people, and you know what I'm happy about? Because I've been saying it for a long time. Forty-six per cent were the Hispanics – 46 per cent, number one with Hispanics. I'm really happy about that."

And it was true. Mr Trump had won Nevada by a margin high above expectations and among voters who at a glance had no business supporting him.

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The thrice-married real estate mogul won among Republican Evangelicals. Having vowed to round up and deport 11 million mainly Hispanic undocumented immigrants, he won among Republican Hispanics.

Famous for lambasting perceived female critics as being fat, or ugly, or menstruating, he won among Republican women.

In the words of a Fox News political editor, "bladder-voiding panic has come to official Washington".

The Republican establishment loathes Mr Trump not only because so many see him as unfit for office, and not just because they don't believe he could win a presidential election, but because they do not consider him to be a true conservative, let alone a true Republican.

This election is a rejection of the globalist economic agenda, failed immigration policies, and rule by the donor class

Even if you take his claim to have back-flipped on his former pro-abortion stance ("Nobody reads the Bible more than me," he chirped with a straight face during his Nevada victory speech), Mr Trump's protectionism and populist support for government programs like Medicare and Medicaid horrify orthodox conservatives, while Wall Street Republicans are appalled by his violent anti-immigration stance.

But rather than uniting party elders the Trump surge has further divided the Republican establishment into those few who would make peace and reason with the invader, and those who would like to see him destroyed.

Mr Trump would "probably work with Congress. He's got the right personality and he's kind of a deal-maker", the former Kansas senator and 1996 Republican nominee Bob Dole told the New York Times optimistically earlier this month, perhaps more a mark of his loathing for Mr Cruz than anything else.

"You can coach Donald. If he got nominated he'd be scared to death. That's the point he would call people in the party and say, 'I just want to talk to you'," lobbyist Charles R. Black chimed in.

Leading the conservative charge against Mr Trump is the movement's pre-eminent publication the National Review, which in late January devoted an issue to attacking him, gathering contributions from nearly two dozen of the movement's best known advocates.

Ramesh Ponnuru​, a senior editor with the National Review, told another magazine, Maclean's, this week that the goal was to, "persuade those people who might be persuadable that supporting Donald Trump is a serious mistake".

Meanwhile, at least three conservative political action committees are now raising money solely for the purpose of attacking Mr Trump, but so far their spending has been tiny compared with the big guns in the race, such super PACs run by mega donors like the billionaires Charles and David Koch and the senior Republican strategist Karl Rove.

Indeed according to a new Politico story, those prominent figures are avoiding attacking Mr Trump for fear of retribution.

The Republican establishment is doing all it can to prop up its preferred anti-Trump candidate, Mr Rubio, with senior Republican officials in both Nevada and South Carolina endorsing him.

But though the party establishment's loathing of Mr Trump is real, it has so far proved to be ineffectual.

In no small part this is because the anger of the voters rallying behind Mr Trump is real, and they feel the party has betrayed them by voicing support for their cultural concerns while serving the material interests of the very wealthy.

"The establishment GOP [Grand Old Party] is lying to itself. This election at its core is a rejection of their globalist economic agenda and failed immigration policies – and of rule by the donor class," Laura Ingraham​, a conservative talk-radio host and political activist, told the New York Times recently. "Millions want the party to go in a more populist direction."

And so the fight is being largely left to the candidates, who so far have failed to dent Mr Trump.

The party hoped that Mr Rubio would absorb support that might have flowed to Jeb Bush when Mr Bush pulled out of the race, but Mr Trump appears to be attracting as much support from those voters as Mr Rubio is.

The next major set of contests is so-called Super Tuesday on March 1, when 11 states will hold contests accounting for 595 Republican delegates – about a quarter of those needed to secure a victory.

Super Tuesday plays to Mr Trump's strengths.

The campaign turns into a national battle, as the candidates leave behind single-state retail politics and fight what is a defacto national campaign.

Candidates will increasingly be forced to rely on hugely expensive television advertising to attract voters, something very few candidates can afford to do.

The campaigns of Mr Rubio and Ohio governor John Kasich have less than US$7 million between them. Mr Trump, by contrast, is a billionaire who has already lent millions to his campaign and will surely do so again. What's more, perhaps no presidential candidate in American history has proven so adept at attracting "free media" – getting the media to put him on the air for free – because his appearances guarantee higher ratings.

Every television appearance serves as an advertisement and nobody makes as many appearances on television as Mr Trump.

It is entirely possible that it is already too late for the GOP to stop Mr Trump, that the establishment waited for the storm to blow over while it only gathered strength, and that the candidates wasted time and political capital attacking one another rather than the leader.

One prominent Washington Post political columnist has already started speculating as to who Mr Trump might pick as a vice-presidential candidate, a pursuit that would have been seen as absurd until recently. (Yes, Sarah Palin is on the list.)

Given their predicament, American conservatives with an eye to history might be prompted to cast their minds back to the words of the founding fathers who debated the shape of the new republic in the writing now known as the Federalist Papers.

One of them, John Jay, warned in 1815, that: "Pure democracy, like pure rum, easily produces intoxication, and with it a thousand mad pranks and fooleries."